Hydraulic pump or motor



May 15, 1962 R. w. BRUNDAGE 3,034,447

HYDRAULIC PUMP OR MOTOR Filed May 19. 1959 3 Sheets-Sheet 1 B MIDLINEFIG. 2

22 IN VEN TOR.

ROBERT W. BRUNDAGE ATTORNEY May 15, 1962 R. w. BRUNDAGE 3,034,447

HYDRAULIC PUMP OR MOTOR Filed May 19, 1959 3 Sheets-Sheet 2 A MIDLINEFIG. 3

, INVliWT0R-. ROBERT W. BRUNDAGE- BY g E ATTORNEY y 1952 R. w. BRUNDAGE3,034,447

HYDRAULIC PUMP 0R MOTOR Filed May 19, 1959 3 Sheets-Sheet 3 FIG. 5

WQE TOR.

ROBERT w. BIBLINDAGE BY ATTORNEY United States Patent 3,034,447HYDRAULIC PUMP R MOTOR Robert W. Brundage, Willoughby Lake, Ohio FiledMay 19, 1959, Ser. No. 814,319 9 Claims. (Cl. 103-426) This inventionpertains to the art of hydraulic pumps or motors, and more particularlyto a hydraulic pump or motor of the positive displacement revolvingchamber type.

The invention is particularly applicable to what is generally known asinternal gear type pumps or motors, and will be described withparticular reference thereto, although it will be appreciated that theinvention has broader applications and in many instances is equallyapplicable to vane or rotating cylinder type hydraulic pumps or motors.

, Furthermore, the present invention is particularly applicable tohydraulic pumps or motors operable at what may be termed very highhydraulic pressures, that is to say, above 1,000 pounds per square inchand oftentimes approaching or exceeding 4,000 pounds per square inch. Atsuch pressures, construction and expedients usable at the lowerpressures are often unsatisfactory and inapplicable to the problems ofhigher pressures.

For the purpose of simplicity, the invention will be described only inrelation to a pump and reference will be made to inlet and outlet ports,inlet and outlet manifolds and increasing and decreasing volumechambers, all of which will be at low and high pressures respectively.The description may be applied to a hydraulic motor by reversing therelationship of the high and low pressures.

Internal gear type hydraulic pumps are normally com prised of aninternally-toothed and an externally-toothed gear member rotating onspaced axes with the teeth in sliding, sealing engagement, all within aninternal cavity of a housing; A shaft extends from the outside of thehousing through this cavity and is supported for rotation within thehousing on spaced bearings with the externally-toothed gear mounted onthe shaft between these bearings. The internally-toothed gear in turn ismounted for rotation on an axis spaced from that of the shaft by meansof an eccentric ring supported within the housing. Sealing membersengage each axial face of the gear members so that when the gear membersrotate, the members define a plurality of chambers which revolve aboutthe axes and, depending upon their position with relation to the planecontaining the spaced axes, progressively increase from a point ofminimum volume corresponding to closed gear mesh to a point of maximumvolume corresponding to open gear mesh and then decrease in volume tothe point of minimum volume. Normally chambers which are decreasing involume all communicate with a discharge port and are at high hydraulicpressures, while the chambers which are increasing in volume allcommunicate with an inlet port and are at relatively low pressures.

It will be appreciated that the high hydraulic pressures arenon-symmetrically located relative to the axes of rotation and createnon-symmetrical forces, both axial andradial, of a very substantialmagnitude on the various parts and members of the pump. It is thedeleterious effects of these non-symmetrical forces with which thepresent invention primarily deals.

Thus the high pressure fluid in the decreasing volume chambers exerts avery high force on one outwardly facing surface of the externallytoothed gear. This force is on the radial line through the center of allthe high pressure chambers and this radial line with the axis ofrotation forms what will hereinafter be referred to as the force plane.This force is transmitted first ice to the shaft and then to thebearings, all in the force plane.

Because of the magnitude of this radial force, sleeve bearingsheretofore could not be employed to rotatably support the shaft, and ithas been considered necessary to use the much more expensive and bulkyroller or ball bearings.

In accordance with the present invention, however, a sleeve-type bearingis employed and the problems heretofore existent therewith are preventedby communieating controlled amounts of the high pressure hydraulic fluidto the inside of the sleeve bearing in a point or line locateddiametrically opposite from the high pressure chambers and on the forceplane. This hydraulic fluid exerts a hydraulic force on the shaft inopposition to the radial force on the externally-toothed gear andeffectively counterbalances it. The loading on the sleeve bearing isthus either eliminated or reduced to a degree where a sleeve bearing iscapable of carrying the load.

As a result of the present invention, it was further found that theforces on the externally-toothed gear were transmitted to the shaft at apoint generally midway between the bearing supports for the shaft andbecause of the magnitude of the force, the shaft was deflected or flexedslightly in an amount proportional to the hydraulic pressure. Thus ifthe sleeve hearings were aligned with the shaft at zero pressure, theywere out of line with the shaft when the pump was operating underpressure and excessive bearing wear occurred.

In accordance with the present invention, this problem is solved bymounting the sleeve hearings in the housing for a pivoted movement inthe radial force plane. The sleeve bearing is thus automatically able tochange its position in the housing and remain in alignment with theshaft even though the shaft is slightly flexed under the effects of thehydraulic forces.

The high pressure hydraulic fluidin the high pressure chambers alsoexerts a radially-offset axial force on each of the sealing members,also in the force plane. This force tends to turn the sealing members ina direction such that the sealing pressures between the sealing membersand the gear faces adjacent the high pressure chambers, where thesealing pressures are really needed, was substantially less than thesealing pressures adjacent the low pressure chambers where the sealingpressures are not needed.

In accordance with the present invention, this problem is solved bypivotally mounting at least one of the sealing members in the housingabout a point in the force plane and providing a radial force in theforce plane on the sealing member so located relative to such point asto pivot the sealing member about the point in a direction to increasethe pressure on the gear face adjacent the high pressure chambers suchthat a more uniform sealing pressure of the sealing member across theentire gear face results.

This radial force tending to so pivot the sealing member in theindicated plane may be derived from the unbalanced radial force of thehydraulic fluid in the high pressure chambers transmitted-to the shaftand thence to the sealing member to the housing, or may be created byexposing non-symmetrical areas of the sealing member to the highpressure fluids, or both.

A still further problem with internal gear type hydraulic pumps has beento maintain the gear teeth at open mesh in sealing relationship as thevarious parts of the pump wear in use to thus prevent leakage betweenthe teeth at this point.

In accordance with the invention the eccentric bearing ring (in whichthe internally-toothed gear rotates) is radially movable within thehousing cavity and means are provided for urging or biasing the teeth ofthe internfllytoothed gear at open mesh toward the teeth of theexternally-toothed gear. The result is that as the parts of the pumpwear, the clearances normally created thereby will be automaticallytaken up within the range of movement of eccentric ring in the'housing.

A still further problem with hydraulic pumps has been the bulk andcomplexity of the housing necessitated by the extremely high forces ofthe hydraulic pressures. The housing provides the physical support forthe various members of the pump to hold them in proper sealingrelationship. It has been conventional in all high pressure hydraulicpumps to provide thevarious'parts of the housing with flat abuttingsurfaces and to hold these parts in assembled relationship by means of aplurality of bolts, studs, dowel pins 'or the like. A threadedengagement of the various parts of the housing has been completelyunsatisfactory because of the clearance apparently necessary in thethreads. Thus the high forces involved caused a slight cocking orshifting of one of the parts of the housing relative to the otherresulting in a misalignment and a separation of the pump sealingsurfaces.

In accordance with the present invention, the housing is formed in twoparts which are threadably engaged one with the other and the members ofthe pump, e.g. the bearing and sealing member relying on at least one ofthe housing parts for physical support are pivotally supported therebysuch that when the said one housing part shifts relative to the other,such shifting is not transmitted to the said members of the pump. 7 Theprincipal object of the present invention is the provision of a new andimproved hydraulic pump or motor which is relatively simple inconstruction, which can be manufactured for a minimum cost, and whichhas a high volumetric and mechanical etficiency.

Another object of the invention is the provision of a new and improvedhigh pressure hydraulic pump or motor which may successfully employrelatively inexpensive sleeve type bearings.

Another object of the invention is the provision of a, pump of thegeneral type described wherein the sealing members will have a uniformsealing pressure against the end faces of the gears.

* new and improved hydraulic pump or motor of the type described,wherein one or both of the partsof the housiug may be formed byrelatively inexpensive impact extrusion processes.

Yet another object of the invention is the provision of .a new andimproved internal gear type hydraulic pump or motor wherein the wear ofthe parts norm-ally permitting leakage at open mesh is automaticallytaken up.

The invention may take physical form in certain parts and arrangement ofparts, the preferred embodiments of which will be described in detail inthis specification and illustrated in the accompanying drawings whichare a part hereof and wherein;

FIGURE 1 is a side cross sectional view of a hydraulic pump or motorillustrating a preferred embodiment of the invention.

FIGURES 2 and 3 are cross sectional views of FIG- URE 1 takenapproximately on the lines 2-2 and 33 thereof, respectively. j I

-F1IGURE 4 is a cross section view of a bearing memher; and

FIGURE '5 is a view similar to FIGURE 1 but illustrating an alternativeembodiment of the invention.

Referring now to the drawings wherein'the showings are for the purposesof illustrating a preferred embodiment of the invention only, and notfor the purposes of Iimitingsame, the figures show what mayalternatively be used as either a hydraulic pump or a hydraulic motor,

but which for the purpose of simplicity, will be described simply as ahydraulic pump. a

The pump of FIGURE 1 includes a housing H, having an interior pumpingcavity in which are mounted a plurality of pumping members defining aplurality of closed chambers which progressively increase and decreasein volume as the members move relative to each other. While such membersmay take a number of conventional forms such as rotating cylinders withaxially reciprocating pistons, rotating vanes, in the embodiment shownthey comprise generally an externally toothed gear member 11, aninternally toothed gear member 12, a sealing member 13 and a manifoldmember 14 engaging the righthand and left-hand axial faces of the gears11 and 12 respectively. r

The gear member 11 is slidable on and keyed to a rotatable shaft 16 bymeans of a key 18 and a key way 19 on the member 11. The internallytoothed gear member 12 is supported for rotation about an axis, spacedfrom the axis of the shaft 16 in a bearing member 17 which,

as will appear, is loosely mounted within the housing cavity. The gearmember 12 has one or more teeth than that of the gear member 11land-these teeth are in sliding, sealing engagement so that as the gearmembers 11 and 12 rotate, they along with the sealing and manifoldmembers 13 and 14 define a plurality of closed chambers revolving on aclosed path of movement and which progressively increase in volume froma point A of a minimum volume to -a point B of maximum volume and thendecrease to the point of minimum volume A. The points A and B are onwhat may be termed the neutral plane through the two axes of rotationand it will be further noted that the gear teeth at the point A are inwhat may be termed closed mesh and at the point B at open mesh.

Housing The housing H in the embodiment shown is formed in two parts,namely, a main part 20, generally in the shape of a cup, and a closurepart 24 over the open end of the cup 20, both parts being so arranged asto have radially opposed surfaces relative to each other. Opposedaxially facing surfaces between the axial ends of the radially opposedsurfaces such as'th'reads 25 retain the part 24 in assembledrelationship with" the cup '20. An Q-ring 26 mounted ina groove in theouter surface of the closure part 24. This construction may bedistinguished from conventional. pump housings whereinthe parts have'axially' facing surfaces in abutment and bolts extending through thesesurfaces holding them in assembled relationship. The closure part 24 onthe cavity side of the threads 25 provides a seal to prevent leakage ofhydraulic fluids longitudinally pa'st the threads 25. As will appear,the threaded fit of the closure part 24 and the main part 20 is notparticularly critical in the construction of the pump.

The main part 20 has a pair of external diametrically opposedlongitudinally extending ribs 21, 22 and on the inside has a pluralityof inwardly facing cylindrical surfaces 27, 28, 39 (reading from left toright), each of which is larger than the predecessor for receiving andcoacting with the various parts or members of the pump itself as willappear. a

In a like manner, the closure part 24 has a plurality of cylindricalsurfaces 32, 3 3, 34 (reading from right to left), each of which islarger than the predecessor.

In the preferred embodiment, both of the parts 20, 24 are preferablymade from aluminum and by virtue of the symmetry thereof, can be formedfrom impact extruded aluminum. Furthermore, because'of the design of thepump as will appear, the diameters and tinishe of the cylindricalsurfaces 27, 28, 29, 30, 3'2, 33, 34 can have rather rough tolerances,and a rough finish,

as may be characteristic of impact extrusion tools as well as the slighttaper necessary to effect withdrawal of the extrusion die.

It is to be further noted that the threads must have a slight clearancefor ready assembly. Such threads under the high pressure forces whichwill be developed on the inside of the housing H permit the closure part24 to cock slightly with reference to the main part 20. However, becauseof the mounting of the pump members relative to the closure part 24,this cocking is not a problem.

Shaft and Bearings In the embodiment of the invention shown, the shaft16 extends through an opening 36 in the left hand end or base of themain part 29 and its left end in the housing H is rotatably supported ina bearing member 37 while its right hand end in the housing H isrotatably supported in a bearing member 38 with the gears in between.

The bearing member 37 is loosely mounted in the portion of the cavitydefined by the cylindrical surface 27 in a manner so as to pivotrelative to the housing H. Thus, in the embodiment of the inventionshown, the bearing member 37 has a cylindrically extending bead 3?around its outer surface having a rounded or circular contour incross-section, the outer diameter of which bead is just slightly lessthan the diameter of the surface 27 so that the bead engages the surface27 at the point of tangency only.

In a like manner, the bearing member 38 is mounted for pivoted movementin the sealing member 13 and for this purpose has a circumferentiallyextending head 40 with a circular contour in cross-section on its outersurface which is loosely engaged in a cylindrical opening defined by asurface 1 in the right hand end of the sealing member 13.

Sealing and Manifold Member The sealing member 13 in turn is mounted fora pivoted movement in the closure part 24 and for this purpose has acircumferentially extending bead or flange 42 with a circular contour onits right hand end which has a diameter slightly less than the diameterof the surface 32 and is loosely fitted into the cavity formed by suchsurface. An O-ring 44 just to the left of the bead 42 fits around theright end of the sealing member 13 and is in sealing engagement with thecylindrical surface 33. This O-ring 44 seals the cavity 45 which is athigh fluid pressure from the cavity 47 which, a will appear, is at lowhydraulic pressure.

A coil spring 43 bears between the right hand end of the sealing member13 and the shoulder 49 of the closure part 24, between the cylindricalsurfaces 33, 34 and biases the sealing member 13 into sealing engagemenwith the right hand end of gear 11, 12.

The manifold member 14 is generally in the shape of a disc and ispositioned, with an interference fit in the cavity defined by thecylindrical surface 29 and rests against the shoulder 52 formed betweenthe cylindrical surfaces 28, 29. The manifold member 14 has a sealingsurface 53 in sealing engagement with the left hand side of the gears 11and 12, and this surface has an arcuate extentfing port 54 formedtherein generally in the path of movement of the pumping chambers. Apassage 55 communicates the port 54 with the outer periphery of themanifold member 14 and thus with the cavity 57 formed between the outerperiphery of the manifold member 14 and the cylindrical surface 30.'Ihe'housing 29 has an opening 58 extending from the outer surface ofthe rib 22 inwardly to communicate with this cavity 57 and forms theoutlet for the pump shown. It will be noted that the passage 55 isdiametrically opposite from the opening 58 so that the outlet fluid fromthe pump flows circumferentially through the cavity 57 and thence outthrough the outlet 58. This path of fluid flow contributes to thecooling of the gear members 11, 12 and manifold member 14.

The manifold member 14 also has an arcuate extending port 60diametrically opposite from the port 54 and identically shaped thereto,which port 60 is in the path of movement of the pumping chambers andextends axially through the manifold member 14 to communicate thepumping chambers with the cavity 61 defined by the.

cylindrical surface 28. An opening 62 through the rib 21 communicateswith this cavity 61 and forms the inlet for the pump. It will be notedthat the inlet opening 62 is diametrically opposite from the port 60 andinwardly flowing hydraulic fluid thus flows over the bearing 37 andgives a cooling effect thereto.

The sealing surface 53 of the manifold member 14, as shown and with theexception of the passage 55, completely surrounds the ports 54, 66 toform between the zucuate ends thereof, lands 64, 65, each of which havea line of movement width slightly greater (by about 10%) than the lineof movement width of the opening 55 from the pumping chambers to theports 54.

If, however, a ported plate is employed as is described in my co-pendingapplication, Serial No. 656,117, filed April 30, 1957, now Patent No.3,007,418, issued Novembet 7, 1961, then the line of movement width ofthe opening from the pumping chambers will be substantially reduced andthe line of movement width of the lands 64, 65 may be substantiallyreduced.

Furthermore, in the embodiment of the invention shown, the ports 54, 60each have the same line of movement width and the lands 64, 65 aresymmetrically disposed about the neutral plane through the axis ofrotation. The manifold member is held from rotating by an interferencefit with the housing surface 29.

Eccentric Ring Member The eccentric ring member 17 rotatably supportsthe gear member 12 and the center or axis of its inner surface coincideswith the axis of rotation of the gear 12. The'outer cylindrical surface67 of the ring member 12 is eccentric to the inner surface and thus tothe axis of rotation of the gear 12 and as an important part of thepresent invention has an outer diameter less than the diameter of thesurface 30. The ring member is thus relatively free to move radially inthe housing 20, but

is held against rotation by a pin 68 extending from the manifold member14 into a slot 69 of the member 17. The eccentricity of the ring member20 is thus located relative to the lands 64, 65 so that the diametricalline through the middle of the lands corresponds to the neutral axis AB(hereinafter called mid line).

it is to be noted that the hydraulic pressures exert forces over a widecircumferential width of the chambers but for the purpose of thisinvention these forces may be all summed up by a single large radialforce Which swings or oscillates about the perpendicular to the land midline as chambers come newly into communication with the dischargemanifold or go out of communication therewith. This force is indicatedgenerally in FIGURn 3 by the vector 70 and for the purposes ofdescribing the invention, its line of action is assumed as being on theradial line perpendicular to the mid line through the lands 64, 65 onthe high pressure chamber side 'of such line. This line of action withthe axisof rotation defines a force plane."

In the embodiment of the invention shown, the lands 64, 65 aresymmetrical with the neutral axis AB and thus the vector 70 isperpendicular to this neutral axis AB. This force urges or biases theeccentric ring radially toward the housing.

In accordance with the invention, the ring member 17 engages the housing20 at a single point located on this line of action. The point or linemay be located in any one of a number of difierent ways, but in theembodiment shown, the eccentric ring has a flat 72 formed on its outersurface with the exception of a single point 73 close to the middle andthis point bears against an i sert 74 mounted on the surface 30 andhaving a'surface 75 provided for continuously biasing or urging theteeth at open mesh'toge ther. In the embodiment shown such meansincludea-leaf spring 71 mounted in a circumfer- 'entially extending groove orslot 79 in the outer surface67 of the member 17 symmetrical about theneutral axis AB. The ends of the spring bear against the I housingsurface 30 and the center against the member All gears have a slightvariation in the height of the gear teeth, In the construction shown,the gear teeth at open mesh take the position of the highest teeth,friction between the gears and the other pump members holding the gearsin this position for one revolution when the highest teeth again touchand locate the gears for the next revolution.

The force vector 70 as shown in FIGURE 3 and FIG- The same hydraulic 1pressure exerts an equal and opposite force indicated URE l is in anupward direction.

by the vector 76 on the axial mid-plane of the gear 11', which force inFIGURE 1 isin a downward direction. This force is transferred from thegear 11 tothe shaft 16 and thence to the two bearings 37, 38 in inversepro- Q portion to the axial centerline distance of the bearings 37,

38 from the axial mid-plane of the gear 11, The force transmitted to thebearing member 37 is then transmitted to the cylindrical surface 27through the spherical surface on the flange 39 all on the force plane.

' In a like manner, the bearing member 38 engages the surface 41 of thesealing member 13 at a point 81 also located on the force plane. V 7

With this arrangement, it will be appreciated that the bearing members37, 38 each'pivot about the support .points 77, 81 respectively so thatas the shaft 16 is deflected asar'estrlt of the force vector 76, thebearing members 37, 33. may deflect therewith resulting in a uniformpressure loading of the shaft 16' along the bearing surfaces of thebearing members 37, 38.

It will be appreciated that in a high pressure pum V the force vect'or76 is very large and the pressures of the shaft 16 on the bearingsurfaces of the bearing members 37, 38 is very substantial and in manyinstances greater than a conventional sleeve type bearing is capable ofhandling.

In accordance with the invention, the high pressure fluid of the pumpiscommunicated to the space between the shaft 16 and the bearingsurfaces of the bearings 37, 38 in a controlled manner so that thehydraulic fluid will exert an upward hydraulic force on the shaft 16 inan amount such that the loading of the shaft 16 on the bearings 37, 38will be within that which the bearings are capableyof withstanding.Preferably the amount is equal to the radial force of the shaft 16 onthe respective bearing. In the embodiment of the invention shown, thebearing surface 83 of the bearing 38 has a diamondshaped groove 84formed therein, symmetrical about the force plane and so dimensionedthat the circumferential corners 85 are spaced 'an arcuate distance lessthan 180 and so that the axial corners 86 are spaced from the axial endsof the surface 83. A circumferential groove 87 interconnects the corners85.

Hydraulic fluid at the high pressure of the pump is supplied to thesegrooves. In the embodiment of the invention shown, a radial passage 88located on the force plane and midway between the axial ends of thebearing member 38 is provided, which passage is aligned with acorresponding passage 853 t rough the sealing member 3.3. it will benoted that the passage 8% is symmetrical relative to thebead 4t) and hasa diameter less than the width of the head 44 so that, in sheet, aportion of the. head 40 which engages the surfaced]. is a circlesurrounding the passage 83.

The cavity 46'communicates with the outlet 58 throughby the diamondshaped groove 84 is generally at the high hydraulicpressure and thispressure exerts an upward force in the shaft 16. By varying the size ofthe diamond, this force may be varied.

The fluid from the diamond groove 84 flows axially along the shaft 16and is discharged into the cavity 47. This cavity is at inlet pressureby virtue of the clearances between the bead wand the surface 36, thekey-way l9 and the space or clearance 92 between the manifold member 14and right hand end of the bearing member 37.

The bearing surface of the bearing member 37 is constructed in a mannersimilar to the bearing surface of the bearing 38 and will not bedescribed further herein. Sufiice it to say that a passage 195 from thecavity 57 communicates the high pressure to the grooves.

It will be appreciated that the hydraulic pressures in the pumpingchambers also exert an axial-force indicated generallylby the vector 9%onthe sealing member 13. Such axial force is in the force plane andtends to move the sealing member 13 'tothe right. This force 94 isopposed primarily by the force of the hydraulic fluid in the cavity 46against the right hand axialiy facing surface 93 of. the sealing member13, which force is axially symmetrical relative to the member 13 and isindicated by the force vector 95. The force vectors 94, 95 are equal andopposite, but are radially off-set one from the other by a distance rwith the result that the sealing member has a turning moment or forcecouple which tends to turn the sealing member 13 away from the gears 11,12 at the high pressure chambers. To prevent this, the inventioncontemplates providing a radial force on the sealing member so locatedrelative to the point of support of the sealing member in the housingthat an opposite turning moment on'the member is created.

. In the preferred embodiment, the radial force is provided from theforce 76. Thus, the portion of the force 76 which is. transmitted to thebearing member 38, is in turn transferred through the bead 40 to thesealing member 13 as indicated by the vector 100. The force 104 isopposed by an equal and opposite forcelfll at the point of engagement ofthe bead 4-2 with the surface 32. It is to be noted that this point ofengagement is on the axial side of the force transferral from thebearing 38 to the sealing member 13 remote from the gear 11, 12. Byproperly proportioning the axial length 1 between the forces and 1M, atthe time of design of the pump, the turning moment on the sealing member13 may be proportioned to be equal and opposite to the turning moment ofthe force vector 94-,

It will be appreciated that the force 94' also tends to separate themanifold member 14 from the gears 11, 12 but as the gears are axiallymovable on the shaft, the forces on the sealing member 13 aretransmitted through the gears 11, 12 so that with the construction abovedescribed, both member 13 and 14 have a pressure sealing engagement withthe axial ends of the gears which is uniform over the entire axiallyfacing surface thereof.

FIGURE- shows an alternative arrangement for holding the sealing memberand manifold member in uniform pressure sealing engagement with theaxial ends of the gears. I-Iere like parts will be designated with like.numbers and similar parts will be designated with a like number with aprime mark at it.

in the embodiment of FIGURE 5 the principal diffcrence is that both thesealing member 13 and the manifold member 14 are loosely mounted in thehousing for pivoted movement about a point in the force plane and theforce for creating the turning moment on these members in opposition tothe force 94 is created hydraulically by exposing unsymmetrical areas ofthe members to the high pressure fiuids with the centers of the areas solocated relative to the pivot point that the required turning moment orforce is created. While this embodiment of the invention shows both thesealing member and the manifold member as being so pivoted, it will beappreciated that the same end result can be obtained by hedly mountingone of the members and increasing the unsymme'try of the other.

In FIGURE 5 the high pressure chambers as distinguished from FIGURE 1are in the lower half of the figure and the housing part 2% has innercylindrical surfaces 27, 29', 313 of progressively increasing diametersreading from left to right. The closure part has cylindrical surfaces32, 34 of progressively increasing diameters reading from right to left.

The scaling member 13 has cylindrical surfaces 159, 11% of progressivelyincreasing diameters from right to left separated by a shoulder 111facing axially away from the gears 11, 12. The surfaces 1139, 11% are ofa diameter less than and loosely fit within the cavities defined by thesurfaces 32', 34. An G-ring 113 in a groove 114 provides a seal betweensurfaces 16 9, 32.

The cavity thus formed to the right of O-ring 113 communicates with thelow pressure chambers through the space between the bearing member 38and the surface 8% and thence to a radial passage 124) in the sealingsurface of the member 13' extending outwardly to the line of movement ofthe low pressure chambers.

The surface 189 has a cylindrical bead 121 just to the left of O-ring113 although it could be to the right of O-ring 113 of a diameterslightly less than surface 32 which engages surface 32' at one point oftangency only on the force plane. The sealing member 13 is otherwisefree to move radially in the housing and pivot about this point.

A second O-ring 115 between surface 109 and surface 34' and bearingagainst the shoulder 111 defines a cavity 116 which is communicated withthe high pressure chambers through a passage 117 opening through thesealing member sealing surface in the line of movement of such chambers.

The left hand side of the O-ring 115 also communicates with the lowpressure chambers through the space between the eccentric ring 17 andthe surface and inlet opening '62.

In accordance with the invention, the plane of shoulder 111 and thusO-ring 115 is oblique to the axis of shaft 16 and inclined symmetricallytoward the high pressure chambers and away from the low pressurechambers so that the area of the portion of the surface 109 between theO-rings and on the high pressure side of the axis is greater than thearea on the low pressure side, the differential area being a function ofthe angle of inclination and having a center n on the high pressure sidemidway between the axially transverse planes through the axial limits ofthe O-ring 115 and on the force plane.

The high pressures in the cavity defined by the two O-rings cxert bothan axial force 95' on the shoulder 111 equal and opposite to the force94 and a radial force 125 on the center end proportional to thedifferential area. As the center n and the line of action of the force125 is spaced a distance P from the line of bead 121, a turning momenton the sealing member 13' is created tending to rotate the member towardthe high pressure chambers and thus oppose the turning moment of theforce 94. 7

It will be appreciated that by inclining the plane of the O-ring 115 inan opposite direction and by placing th point of tangency contact of thesealing member 13 with the housing between the O-ring and the gears 11,12, a similar turning moment can be created.

In a similar manner the manifold member 14' has cylindrical surfaces130, 131 of increasing diameters reading from left to right separated bya shoulder 132 facing axially away from the gears 11, 12. The surfaces139, 131 are of a diameter less than and loosely fit within the cavitiesdefined by the surfaces 27, 29. An 0- ring 133 in a groove 134 providesa seal between surfaces 139, 2.7. p

The cavity to the left of O-ring 133 communicates with the low pressurechambers through the space between the bearing member 37' and the innersurface 135 of an axially extending bore in the manifold mombar 14- andthence through a radial passage 136 communicating with the inlet opening62'.

The surface 139 has a cylindrical head 133 just to".

. the left of G-ring 135 of a diameter slightly less than the surface27' which engages surface 27 at one point of tangency only on the forceplane. The manifold member 14' is otherwise free to move radially in thehousing and pivot about this point.

A second O-ring 1413 between surface 131 and surface 27 and bearingagainst the shoulder 132 defines with the O-ring a cavity into which theoutlet manifold 54 discharges and which is communicated with the outletopeuing 53.

The right hand side of the O-ring 141) is in communication with theinlet opening 62'.

In accordance with the invention, the plane of shoulder 132 and thusO-ring 140 is oblique to the axis of shaft 16 and inclined symmetricallytoward the high pressure chambers and away from the low pressurechambers so that the area of the portion of the surface 130 between theQ-rings 135, 141 on the high pressure side of the axis is greater thanthe area on the low pressure side of the axis. The differential area isthe function of th angle of inclination and has a center s on the highpres-' sure side midway between the axially transverse planes throughthe axial limits of the 0-ring 14f The high pressures exert both anaxial force on the shoulder 132 equal and opposite to the force 74 and aradial force 151 on the center s proportional to the differential areaand as this center is spaced a distance r from the plane of head 138 aturning moment on the manifold member 14' is created tending to rotatethe member toward the high pressure chambers and thus oppose the turningmoment of the force 74.

It will be appreciated that the turning moment on either of the members3' or 14 may be varied or adjusted by two expedients, namely, changingthe inclination of the planes of the 0-Iings or changing the distancefrom the center of the differential pressure areas from the point ofcontact with the housing or both.

It will further be appreciated that either the manifold member orsealing member or both may be mounted as above described.

In connection with either embodiment of the invention, it is to be notedthat the closure part 24 with reference to the main part 213, because ofthe necessary clearance between the threaded engagement, may cockslightly under the force of the high pressures on the inside of thepump. In the present invention this is not detrimental for the reasonthat the sealing member 13 is pivoted relative to the closure part 24and when the part 24 cocks, this twisting or turning is not transmittedto the sealing disc 13.

It is to be further noted that with reference to the embodiment ofFZGURE 1, the internally toothed gear 12 rotates within theeccentricbearing ring 17 and is ll" lubricated by the fluid being pumpedat thehigh discharge pressure. Inasmuch as the viscosity of the fluidincreases with pressure and inasmuch as a high viscosity lubricantis-required to withstand the heavy radial loads,

between the gear and the ring, this is a decided advantage. This isdescribed and claimed in my co-pending application, Serial No. 814,320,filed May 19, 1959.

It will thus be seen that embodiments of the invention have beendescribed in such detail as will enable those skilled in the art toutilize the principles of the invention in the design of high pressure,high efiiciency,

positive displacement hydraulic pumps and/or motors.

The invention has been described in connection with preferredembodiments. fObviously, modifications and alterations will occur toothers upon reading and understanding of this specification and his myintention to include all such modifications and alterations insofar asthey come with n the scope of the. appendant claims.

Having thus described my invention, i claim: 7

1. In a positive displacement hydraulic device comprised of incombination: a housing having an inwardly facing surface defining apumping cavity at least portions of which surface are generallycylindrical; a shaft exten ing into said housing and rotatable on theaxis of said cylindrical portion; an externally toothed gear supportedon said shaft for rotation therewith; an internally toothed gear 'havingteeth in sliding, sealing engagement with said externally toothed gearand rotatable about an axis spaced from said shaft axis by apredetermined gear eccentricity determined by said gear teeth; a bearingring having a radially inwardly facing cylindrical surface rotatablysupporting said internally toothed gear and a radially outwardly facingouter surface; said gear teeth moving from open to closed mesh as thegears rotate and defining a plurality of revolving increasing anddecreasing volume'chanrbers; at least one of said chambers being at highdischarge pressure whereby a resultant V. radially outward force isexerted on said internmly 'toothed gear, the improvement whichcomprises: said bearing ring outer surface having a clearance from saidhousing surface less than said gear eccentricity whereby said ring isradially movable in said housing cavity; and means biasing said bearingring radially inwardly at the open mesh point of said chambers, wherebysaid gear teeth are biased together at the open mesh point thereof. 2.The improvement of claim 1 wherein said means comprise a springmemberdisposed between the bearing ring and said housing surfaceadjacent opening mesh of said gears. I

3. The improvement of claim 1 wherein said bearing 'ring outer surfaceand said housing surface have a point engagement generally on the radialline through the center of the high pressure chambers.

prised of, in combination: a housing having an inwardly facing surfacedefining a pum ing cavity at least portions of which surface arecylindrical; ashaft extending into said housing and rotatable on theaxis of said cylindrical portion; an externally toothed gear supportedon said shaft for rotation therewith; an internally toothed gear havingteeth in sliding, sealing engagement with said externally toothed gearand rotatable about an axis spaced from said shaft axis by apredetermined gear eccentricity determined by said gear teeth; meansrotatably supporting said internally toothed .gear; said gear teethmoving from open to closed mesh as the gears rotate and defining aplurality of revolvingincreasin-g and decreasing volumechambers; asealing member in sealing engagement with one axial end of said gears; amanifold member in sealing engagement with the other axial end of saidgears, the decreasing volume chambers being at high discharge pressurewhereby a resultant radially inward force is exerted on said externallytoothed gear and on said shaft on the same side of the shaft as the highpressure chambers and a radially ofiset axial force is exerted on saidmembers on the same side of said shaft as said high pressure chambers;the improvement which comprises at least one of said members beingloosely mounted in said housing and engaging said housing at a singleradially facing contact point spaced from the axial ber has a radiallyoutwardly facing surface exposed tothe high hydraulic pressure, saidsurface being circumferentially unsymmetrical such that the area of theportion of the surface on the high pressure side of the shaft is greaterthan the area on the low pressure side of the shaft, the size of thedifferential area thereof and the center of such area being locatedbetween said point of contact andsaid axial end of said gears whereby tocreate a radial force onsaid one member, said radial forces on said onemember exerting a turning moment about said contact point to oppose theturning moment of said radially or'fset axial force. a

8. in a positive displacement hydraulic device comprising incombination: a housing having an inner generally cylindrical surfacedefining a cavity, a shaft extendinginto said cavity and rotatably aboutan axis, a plurality of members rotatable with said shaft and defining aplurality of chambers which move on a fixed line of movement, sealingmeans in sealing engagement with each axial end of said members, one ofsaid means having arcuate ports therein communicating with the openingsfrom said chambers as they revolve and diametrically opposed landsspacing the ends of said ports, the line of movement width of said landsbeing slightly greater than the line'of movement width of theopeningsfrom said chambers to said ports, the chambers on one radial side of thediametrical line through the lands being at high fluid pressure wherebya resultant radially inward force is exerted on said shaft on the sameside of the shaft as the high pressure chambers; bearingmembers,

one on each side of said pumping members rotatably supporting said shaftin said housing; the irnprovement which comprises said bearing membersbeing loosely mounted in said housing for pivoted movement relative tosaid housing about a point on the side of said shaft diametricallyopposite from said high pressure chambers.

9. In a positive displacement hydraulic device comprising incombination: a housing having an inner generally cylindrical surfacedefining a cavity, a shaft extending into said cavity and rotatableabout an axis, a plurality of members rotatable with said shaft anddefining a plurality of chambers which move on a closed fixed line ofmovement, sealing means in sealing engagement with each axial end ofsaid members, one of said means having arcuate ports thereincommunicatingwith said chambers as they revolve and a pair ofdiametrically opposed lands spacing the arcuate ends of said ports, theline of movement width of said lands being slightly greater than theline of movement width of the openings from said chambers to said ports,the chambers on one radial side of the diametrical line through thelands being at high fluid pressure whereby a resultant radially inwardforce is exerted on said shaft on the same side of the shaft as the highpressure chambers, and bearing members, one at each axial end of saidpumping members rotatably supporting said shaft in said housing; theimprovement which comprises said bearing members being loosely mountedin said housing and at least on the side of said shaft diametricallyopposite from said high pressure chambers having a circumferentiallyextending surface having a circular contour in cross section and meanssupporting said bearings comprised of a circular surface having adiameter at least slightly greater than the diameter of saidcircumferentially extending portion, said bearing members being free topivot about the point of contact of said surfaces.

References Cited in the file of this patent UNITED STATES PATENTSRotermund Jan. 23, Fitch et al Dec. 19', Hill Aug. 14, Sandberg Feb. 9,Eames May 21, Adams et a1 Oct. 15, Brundage Oct. 18,

FOREIGN PATENTS Great Britain Sept. 11, Germany Apr. 18,

(KL 59c 3/ 01) Germany Apr. 16,

(KL' 59c 3/01) France Apr. 30,

